This relates generally to the formation of active areas in microelectronic devices.
Active areas are areas where transistors may be formed. Generally, active areas are isolated from the remainder of an integrated circuit using local oxidation (LOCOS). Within the active area of a memory there is an array and a periphery. The array is a matrix of memory elements and the periphery is the portion of the active area outside the array.
The LOCOS process does not form, for example, substrate areas of different heights. In charge trapping and phase change memories, array and peripheral areas may be at different heights to allow the right process integration.